A photo released by investigators of a Kazan apartment with a message that appeared to be written in blood.

The bodies of a 76-year-old mother and her 38-year-old daughter were found in their Kazan apartment near a wall daubed with the words "Free Pussy Riot," apparently in the victims' own blood, investigators said Thursday.

A lawyer for three Pussy Riot punk rockers sentenced on Aug. 17 to two years in prison for singing an anti-Putin song in a Moscow cathedral called the English-language message "a dirty provocation."

A senior Russian Orthodox official urged international celebrities like Madonna and Paul McCartney to withdraw their support for Pussy Riot to prevent further killings, while a lawyer for Russian Orthodox believers who sued Pussy Riot for the performance blamed the punk group for the deaths.

The bodies of the two women were found with multiple stab wounds in Tatarstan's capital on Wednesday, the Investigative Committee said in a statement.

Investigators believe the killings of the women, who were not identified, took place sometime between Aug. 24 and 26.

While a Pussy Riot supporter might have been involved, all signs point to a robbery, including the "total mess" in the apartment, said Andrei Sheptitsky, a spokesman for regional investigators.

The killer might have written the message under the influence of alcohol or drugs or "as a cover-up," Sheptitsky said by telephone. Alternatively, he said, the killer might have been "simply insane."

Investigators refused to say whether they had any suspects.

Decrying the bloody message as a provocation, Pussy Riot lawyer Nikolai Polozov said the group's supporters were "mostly people who stick to legal ways of protest," Interfax reported. On Twitter, he warned journalists against calling the killers Pussy Riot supporters.

But a headline Thursday afternoon on state-run news website Vesti.ru seemed to do just that, reading, "People Have Begun to Kill for Pussy Riot."

Mikhail Kuznetsov, a lawyer for the plaintiffs in the trial, said that if the musicians had been convicted of inciting religious hatred, "tragedies like the one in Kazan … would have been avoided," Interfax reported. The defendants were convicted of hooliganism motivated by religious hatred.

Kuznetsov speculated that the masterminds of the February performance in Christ the Savior Cathedral might have been involved in the Kazan killings.

No one has been accused of masterminding the performance, and investigators have not been assigned the task of identifying any masterminds.

The Russian Orthodox Church, which has come under fire for its hard-line stance on the Pussy Riot case, ignored investigators' preliminary findings to lash out at Pussy Riot's many supporters.

Dmitry Smirnov, a department head at the Moscow Patriarchate, said the blood of the Kazan women was "on the conscience of the so-called society" that supports Pussy Riot, according to Interfax. He called on pop stars, human rights groups and politicians to "disavow" their statements of support to prevent further violence.

Meanwhile, a male body with an icon on top was discovered Thursday in the hall of an apartment building on the outskirts of St. Petersburg, Interfax reported. The man appeared to have been stabbed to death. No further details were immediately available.

In addition to the Pussy Riot case, the church has come under a barrage of criticism based on allegations of corruption and coziness with the state. Last weekend, vandals sawed down four Orthodox crosses in two provinces.

Also Thursday, state-run VTsIOM released a poll indicating that 33 percent of Russians think the Pussy Riot sentence was too harsh. Another 31 percent think it was appropriate for what they did, while 15 percent believe the sentence was too light. Ten percent say the women didn't violate the law.

But only 32 percent of the respondents, most of them retirees and wealthy Russians, knew what sentence had been handed down.

The poll was conducted last weekend among 1,600 people in 46 regions. Its margin of error was 3.4 percentage points.